Press or impact apparatus.



L. F. KRISTUFEK.

PRESS 0R IMPACT APPARATUS.

APPLICATION FILED FEB- 9. I916.

' 1,230,492. Patented June 19, 1917. v

4 SHEETS-SHEET 2.

a F a L. F. KRISTUFEK'.

PRESS 0R IMPACT APPARATUS.

APPLICATION FILED FEB. 9, 1916.

4 SHEETS-SHEET 3.

L. FIKRISTUFEK.

PRESS OR IMPACT APPARATUS.

APPLICATION FILED FEB. 9. 1916.

1,230,492. Patented June 19, 1917.

4 SHEETS-SHEET 4.

[WWW

UNITED STATES PATENT ornicE.

LADISLAV F. xms'rurnx, or CHICAGO, ILLINOIS, Assrenon. T0GENEBAILBRI'QUETTINGQ COMPANY, or CHICAGO, ILLINOIS, A CORPORATION orILLINOIS.

'rnnss on mrac'r APPARATUS.

Specification of Letters Patent. Patented 11119 19 1917,

Application filed February 9, 1916. SerialNo. 77,174.

To all whom it may concern Be it known that I, LADISLAV F. KRIST'U- FEK,a citizen of the UnitedStates, residing at Chicago, in the county ofCook and State of Illinois, have-invented certain new and usefulImprovements in Presses or. Impact Apparatus, of which the following isa specification. v

My invention relates to apparatus for exerting pressures or producingstriking impulses, and one of the principal objects of the invention isto provide certain improve.

ments in machinery of this type whereby such machinery will be moreeffective in its operation and the cost of running the same reduced.

A more specific object is to provide a hydraulic press or otherapparatus for exerting pressures or producing impacts of such characterthat steamor other expansible' fluid may be used economically andeflectively as a motive fluid. In this connection the invention consistsin providing certain means whereby the last part of each power stroke ofthe apparatus is intensified and in utilizing the expansive force of thesteam,

cut off from the source of supply for driving the hydraulic plunger orpower element of the apparatus during this part of its stroke. Theinvention makes it possible to use the expansive force of steam in powerpresses, such as briqueting presses for example, or other likeapparatus, with the result that machinery of this sort may be operatedmore'economically than has been heretofore possible.

Viewed more narrowly, my invention has for an object particularly tomake certain improvements upon I the impact apparatus described andclaimed in the application for United States Letters Patent of Marius P.J acominifiled February 9, 1916, Serial-N0. 77172. In the apparatusshown in this application the effective capacity of the by drauliccylinder is suddenly increased during the power stroke of the machine soas to momentarily diminish the resistance of the,

pressure transmitting fluid with the result that the plunger acquires avery considerable momentum subsequently imparted "to the work throughthe ram or impact element. The improvements of my invention consist, inthe first place,'in providing the apparatus with a steam cut-ofl valvewhich operates automatically to cut off the steam from the pacit'y foroperation under different conarticle or material.

parts in the several figures of the power cylinder at approximately thetime that the resistance in the pressure transmitting fluid isdecreased; the further forward movement of the plunger being efl'ectedsolely by the expansive for'ce'of the steam diminished by varying theextent towhich the capacity of the hydraulic cylinder .is enlarged andmeans for regulating the hydraulic pressure tending to return the ram toits initial position; these adjustments giving the apparatus theflexibility and caditions and to produce difl'erent results whichincreases the value of the machine very conslderably.

My invention consists further in a novel method of utilizing steam orother expansible fluid as a motive fluid and subsequentlynon-compressible fluid as a pressure trans- I mitting means in theoperation of pressing or producing, striking impulses upon an Theinvention'is illustrated, in a preferred embodiment, wherein in theaccompanying drawings Figure l is a sectional elevation of a steamoperated hydraulic briqueting press constructed in accordance withthe-principles of the inventionz Fig. 2 is an enlarged longitudinalsectional view of the steam cylinder andthe mechanism forcontrollin theinlet and exhaust valves'thereof, being taken on line a)'b of Fig. 4..

Fig. 3 is a section taken on line 0 Z of Fig. 4.

, Fig. 4 is a plan view of the upper portion of. the apparatus. I Fig. 5is a view similar to Flg. 2 but taken on line H of Fig. 4.

, Figs. v6, 7 and 8 are sectional views of the ram, hydraulic cylinderand plunger showing the ram and plunger in different oper-' atlvepositions.

,Like' characters of reference desi ate like I awings. The base 10 ofthe machine supports an 60 in the cylinder. In the second place, my inanvil block 11 having thereon a lower form or die 12 containing thematerial 13 to be briqueted. The upper or movable die 14 is carried bythe cross head 15 on the ram 16. The latter reoiprocates in a hydrauliccylinder 17 which is supported by pedestals 18 on the base of themachine. Attached to the cross head 15 are rods 19 having pistons 20 attheir lower ends which operate in lifting cylinders 21. 22 is anaccumulator tank connected by a pipe 23, 24 with the cylinders 21. 25 isa fitting interposed between pipe sections 23, 24 having a duct 26 inwhich is arranged an adjustable needle valve 27. This needle valvecontrols the flow of fluid from the accumulator tank to the liftingcylinders. 28 is a bypass around the needle valve provided with a checkvalve 29 which permits the flow of fluid from the lifting cylinders tothe accumulator tank but prevents movement of the fluid through theby-pass in the opposite direction. Compressed air or other pressurefluid is maintained in the accumulator tank at relatively constantpressure. This pressure transmitting fluid consists preferably of oil.

The hydraulic cylinder 17 is formed with a web 31 having a duct 32 whichcommunicates with the accumulator tank through pipe 33. 34 is a checkvalve arranged to permit the flow of fluid from the accumulator tankinto the hydraulic cylinder while preventing movement of the fluid inthe opposite direction.

The plunger 35 is preferably tapered at its extremity as shown at 36,and is carried by a piston 37 in the steam cylinder 38. The

latter has an inlet port 39 and an exhaust port 40.

41 is the inlet valve for the steam cylinder which is controlled by thefollowing mechanism: Valve 41 is carried on a stem 42 which is providedwith an abutment 43 for the forked end 44 of a lever 45 which is keyedto a shaft 46 mounted in hearings on the webs 47 forming a part of theframework of the machine. Shaft 46 is rocked by means of an operatingarm 48 connected to the bell crank lever 49 on the lower part of themachine (Fig. 1) by a link 50. The upper end of the stem 42 enters thedash pot 51 and is provided with a seat member 52. A spring 53 isinterposed between the seat member and the plug 54 which closes the endof the dash pot.

The lever 45 is formed with an upwardly projecting extension 55 carryinga roller 56 adapted to bear against a cam 57 keyed to a shaft 58supported in hearings in the webs 47. Loosely mounted on the shaft 58 1sa bell crank, one arm of which 59 is connected by a link 60 with anenlargement or head 61 formed on a rod 62 which is rigidly connectedwith the steam piston 37. The other arm 63 of the bell crank, 59, 63,carries a.

pivoted dog 64 pressed by a leaf spring 65 and adapted to engage a lug66 on the cam 57. 67 is a roller adapted to be engaged by the cam shapednose 68 of dog 64, the roller being carried on an arm 69 rigidly securedby set'screw 70 to a sleeve 71 loose on shaft 58. 72 is an arm fixed tosleeve 71 by a set screw 73 and connected by a link 74 with an adjustingscrew 75 which carries a pointer 76 operating in connection with a scale77 on a fixed bracket 78. The adjusting screw 75 is moved up and down bya nut 79 which works between webs 80 on the bracket 78. The shaft 58 haskeyed thereto a lever 81 to which is connected by link 82 (Fig. 5) apiston 83 arranged within a dash pot cylinder 84. A spring 85 is.interposed between V the piston and the top of the cylinder.

The exhaust valve 86 is automatically controlled by the followingmechanism: The stem 87 of the valve bears against a forked member 88pivoted to a lever 89 fulcrumed at 90 on stationary Webs 91, 91, formingpart of theframework of the machine. The forked ends 92 of the lever 89are connected by links 93 with a sleeve 94 which is slidably arrangedupon rod 62. The upper end of the sleeve projects into the cylindricalguide 95 in which the head 61 of the rod slides. The sleeve has a flange96 which normally bears against the under side of the enlarged portion97 of the guide 95. The structure 95. 97 is supported upon and securedto the head 98 of the steam cylinder 38. 99 is a dog pivoted betweenwebs 91 and adapted to engage a shoulder 100 on a block 101 arranged inthe fork of lever 89. 102 is a trip lever pivoted to the guide 95 andprovided with a cam face 103 adapted to be engaged by the cam face 104on the head 61. The trip lever is connected with dog 99 by link 105. 106is a leaf spring which bears against the dog 99 and 107 a helical springinterposed between the forked member 88 which carries the exhaustvalvestem and a gland 108 through which the stem of the exhaust valve passes.

The enlargement of the capacity of the hydraulic cylinder whereby theresistance of pressure transmitting fluid is momentarily decreased, ispreferably brought about by the arrangement shown in detail in Figs. 6to 8 inclusive. which are different posi tion figures showing the sameparts. The ram 16 is formed at its upper end with an upstanding flange109 which overlaps the neck portion 110 of the cylinder. When the rammoves downwardly a space or chamber 111 is provided which is put intocommunication with the main space 112 within the ram. The pressuretransmitting fluid rushes into the chamber 111 whereby its resistance tothe movement of the plunger momentarily ceases. A duct 113, 114 leadsfrom the main space 112 in the hydraulic cylinder to the sure againstthe fluid within the hydraulic space or chamber 111. 115 is a needlevalve which is adjustable and projects 'into the portion 114 of thisduct. 116 is a bypass and 117 a check valve arranged in the bypass whichpermits the outflow from cha'mber,111 into the main space in thehydraulic cylinder while preventing flow through the by-pass in theopposite direction.

Operatz'0n.The machine shown in the drawings provides for manualcontrol,that is, each power stroke is brought aboutby manipulation ,of controllever 49. The movements of the parts of the apparatus during each cycleof operation of the machine are automatic. Obviously if desired theactuation of the machine might be' automatic throughout. As shown, steamis admitted 13013118 steam, cylinder 38 by raising lever 49 whichunseats valve 41 against the pressure of spring 53. The movement of, thevalve is efi'ected by rocking the lever 45, 55 from the position shownin Fig. 2 to that shown in Fig. 5. The cam 57 is drawn down against thepressure of spring 85 by the downward movement of the steam piston37'which carries with it rod 62, head 61 and bell crank 59, 63. Plunger35 exerts .prescylinder, forcing the ram downwardly by a pressure whichovercomes the upward hydraulic pressure against pistons 20. The die 14isbrought against the work l3 exerting an initial pressure thereon. 1

. As soon as the flange 109 on the upper en of the ram clears the neck110 of the hydraulic cylinder 17, the/fluid in the main space within theram and cylinder rushes into the chamber 111 so that the pressureconnection between the plunger and ram' is momentarily destroyed. Theplunger makes a jump downwardly, acquiring very considerable momentum.This, in turn, is imparted to the ramas the displacement effected by themovement .of the plunger compensates-for the increased capacity of thecylinder due to the opening of chamber 111. About'the time that theplunger makes its forward jump the nose 68 of dog 64 comes into contactwith the roller 67. Q The dog 1s rocked to trip the cam 57 (Fig. 5) andspring 53 closes the inlet valve 41, shutting ofl" the supply to thesteam cylinder. 1 The expansive force of the steam within the cylindercompletes the stroke of the plunger. The expansive force of the steamoperating against the plunger which for the moment encounterspractically no resistance, imparts a very rapid movement to the plungerwhich, when such movement is transmitted to the ram, causes the latterto deliver asharp,

. quick impulse of very great force against the work. When the steamplunger reaches the bottom of its power stroke the head 61 strikesagainst the sleeve 94, :pushing it downwardly far enough so that the dog99 forced past valve 115 into the chamber 111v partly filling the samebefore the chamber is opened up to the mainspace in the ram andcylinder, the amount depending upon the adjustment of the valve. By thisadjust ment, therefore, the decrease in the resistance of the pressuretransmitting fluid to the movement of the plunger may be varied so as tovary the jump of the plunger and hence the force of the intensificationof the power stroke of the apparatus. I

By setting the pointer 76 at diflerent places/on scale 77 the positionof roller 67 may be varied so as to change the time,'relative to theother movements of 'the machine, at which the steam is shut off from thesteam cylinder 38. By adjusting the needle valve 27 the'action of thepressure fluid on the lifting pistons 20 may be regulated so that thereturn stroke of the ram will be properly timed with reference to theother movements of the apparatus.

operative It will be understood from the foregoing that the invention isnot to be considered as limited to the concrete embodiment thereof shownand described. Thesame principles -of operation may be applied to aconsiderable variety of power driven presses or impact apparatus of onesort or another. mechanical devices and constructions by which theprinciples of my invention are adapted to any particular type ofmachinery are a matter of relatively small importance. 1, therefore, donot wish to be understood as limiting the invention to the, preciseconstructions-arrangements and devices shown The r and described exceptso far as certain of the claims herein are by limited.

I claim: 1. In apparatus of the character described, the-combination ofa power element, an im pact element, means providing a pressuretransmitting fluid between the same, the resistance of which ismomentarily diminished during the power stroke of the appatheir languageso ratus, and regulating means for varying the extent to which saidresistance is diminished.

2. In apparatus of the character described, the combination of a powerelement, an impact? element, confining means for a pressure transmittingfluid inter osed between said elements, the capacity 0 which isincreased during the power stroke of the apparatus so. as to suddenlydiminish the resistance of the extent to which said resistance isdiminished.

3. In apparatus of the character described, the combination of a powerelement, an impact element, confining means for a pressure transmittingfluid interposed between said elements comprising a chamber which is putinto communication with the main space within the confining means duringthe power stroke of the apparatus,and means for varying the effectivesize of said chamber at the time it is put into communication with themain space.

4. In apparatus of the character described,

the combination of a power element, an impact element, confining meansfor a pressure transmitting fluid interposed between said elementscomprising a chamber which is put into communication with the main spacewithin the confining means during the down stroke of the apparatus, aduct leading from said main space into said chamber, and adjustablemeans for regulating the flow of flluid through said duct. 5. Inapparatus of the character described, the combination of a powerelement, an impact element, confining means for a pressure transmittingfluid interposed between said elements comprising a chamberwhich is putinto communication with the main space within the confining means duringthe down stroke of the apparatus, a duct leading from said main spaceinto said chamber, and a needle valve which is adjustable to regulatethe flow of fluid through said duct.

6. In apparatus of the character described, the combination of a powerelement, an impact element, confining means for a pressure transmittingfluid interposed between said elements comprising a chamber which is putinto communication with the main space within the confining means duringthe down stroke of the apparatus, a duct leading from said main spaceinto said chamber, adjustable means for regulating the flow of fluidthrough saidduct, and a by-pass and check valve which permit the outflowfrom said chamber but prevent inflow thereto except as controlled bysaid adjustable means.

7. In apparatus of the character described, the combination of ahydraulic cylinder, a

plunger and a ram in said cylinder, said' cylinder and ram constructedso as to provide a chamber by the movement of said ram into whichpressure fluid within the cylinder is suddenly admitted after the ramhas traveled a certain distance in its power stroke. I

8. In'apparatus of the character described, the combination of ahydraulic cylinder, a plunger, a ram in said cylinder, said cylinder andram constructed so as to provide a chamber into which pressure fluidwithin the cylinder is suddenly admitted after the terior of thecylinder into said chamber, an

adjustable valve for controlling the flow through said duct, and aby-pass and check valve which permit the outflow of fluid from saidchamber while preventing the inflow thereto except as controlled by saidadjustable valve.

10. In apparatus of the character described, the combination of animpact element, a driven element and means for driving the samecomprising a cylinder adapted to receive an expansible fluid, meansconstituting a pressure transmitting connection interposed between thedriven element and.

the impact element, the resistance of which is momentarily diminishedduring thev power stroke of the apparatus, and means for shutting ofl'fluid from said cylinder at approximately the time the resistance ofsaid connection is diminished.

11. In apparatus of the character described, the combination of animpact element, a driven element, and means for driving the samecomprising a cylinder adapted to receive an expansible fluid, containingmeans for a pressure transmitting fluid interposed between saidelements, the capacity of which is momentarily increased during thepower stroke of the apparatus, and means for shutting 0d the expansivefluid from said cylinder at approximately the time thatthe capacity ofthe containing means is increased.

12. In apparatus of the character described, the combination of animpact element, a driven element, and means for driving the samecomprising a cylinder adapted to receive an expansible fluid, containingmeans for a pressure transmitting fluid interposed between'saidelements, the capacity of which is momentarily increased during thepower stroke of the apparatus, means for shutting ofl the expansivefluidfrom said cylinder at approximately the time that the capacityof thecontaining means is increased, and means for varying the extent to whichthe capacity of the containing means is increased. 13. In apparatus ofthe character described, thecombination of an impact element, a drivenelement andmeans for driving the same comprising a cylinder adapted are1 -to receive an expansible fluid, containing means fora pressuretransmitting fluid in terposed between said elements andcomprisinga-chamber adapted to be put into communication'with the main spacewithin said containing means during the power stroke of the apparatus,-and means for shuttlng oif the expansive fluid from said cylinderapproximately at the time that said chamber 1s put into communicationwith the main spacewithin the containing means.

14:- In apparatus of the character described, the combination of animpact element, a driven element and means for driving the samecomprising a cylinder adapted to receive an e xpansible fluid, meansconstituting a pressure transmitting connection interposed between thedrivenelement and the impact element, the resistance of which ismomentarily diminished during the power stroke of the apparatus meansfor shutting I oif fluid from said cylinder at approximately the timethe "resistance of said 0011*, nection is diminished,and means for vary-1ng the exact time at which the expansible fluid is shut ofi from thecylinder.

15. In apparatus of the characterv described, the combination of an imact element a driven element and means or driving the same comprising acylinder adapted to. receive an expansible ,fiuid containing means for apressure transmitting fluid interposed between said elements andcomprising a chamber adapted to be put into commimication with the mainspace within said containing means, a duct leading from said main spacetolsaid chamber, an adjustable valve to control the flow through said"duct, and means for shutting off the expansible fluid from saidcylinder at approximately the time that said chamber is put intocommunication with said. main space.

' 16. In apparatus of the character described, the combination of an ,imact ele; ment, a driven element and means I or driving the samecomprising a cylinder adapted to receive an .expansible fluid, meansconstitutinga pressure transmitting connection interposed between thedriven element and the impact element, the resistance of which ismomentarily diminished during the power a stroke ofvthe ap aratus, andautomatically operated means or shutting oii fluid. from 17'. Inapparatusjof the character described,' the combination of an impactelement, a driven element and means for driv ing the samecomplf sing acylinder adapted to receive an expansible fluid-,means constituting apressure transmitting connection interposed between the dri en lem nt,and

the impact element, the. resistance of which a is momentarily diminishedduring the 'ower stroke oi the. apparatus, agtomatica creased.v saidcylinder at approximately thetime the erated means for shutting offfluid from said cylinder at approximately the time the resistance ofsaid connection is diminished, and means for varying the exact time atwhich expansible fluid is shut oii from said cylinder. J

18.In apparatus of the character de-' scribed, the combination with asteam cylinder provided with inlet and exhaust ports, a pistonin saidcylinder provided with a hydraulic plunger, a hydraulic cylinder inwhich said plunger operates, a ram in said hydraulic cylinder, theaforesaid parts comprising means whereby the efl'ective capacity of thehydraulic cylinder is suddenly increased during the power stroke of theap-- paratus, inlet and outlet valves for the steam cylinder, andautomatically operating means for closing said inlet valve and openingand v hydraulic cylinder, the aforesaid parts com- I prising meanswhereby the eflective capacity of the hydraulic cylinder is suddenlyincreased duringthe power stroke of the apparatus, inlet and outletvalves-for the steam cylinder, automatically operating means for closingsaid inlet valve and opening and closing said exhaust valveflandmeansfor adjusting the time at which said inlet valve is closed.

20. In apparatus of the character described, the combination with asteam cylinder provided with inlet and exhaust ports, a piston in saidcylinder provided with a hydraulic plunger, a hydraulic cylinder inwhich said plunger operates, a ram in said hydraulic cylinder, theaforesaid parts comprising means whereby the eflective capacity oftliehydraulic cylinder is suddenly inparatus, inlet and outlet valvesfor the steam cylinder, "automatically operating means for closing saidinlet valve and opening and closing. said exhaust valve, and means forvarym'g the extent to which the eflective capacity of said hydrauliccylinder is inapparatus of the character described, the combination witha steam cylinderf provided with inlet'and exhaust ports, .a plston insaid cylinder provided with a hydraulic plunger-ya hydraulic cylinder inwhich saidplunger operates, a ram in said hydraulic cylinder, theaforesaid parts comprising means whereby the efi'ective capacity of thehydraulic c'ylln'der is suddenly increased during the. power stroke ofthe ap- "paratus, inlet and outlet valves for the steam cylinder,automatically operating means for conformity with the other operativemovements of the apparatus. a

22. In apparatus of the character described, the combination with asource of supply of expansihle motive fluid, of a cylinder having aninlet port arranged to communicate with said source of supply and anexhaust port, valves to control said ports respectively, a piston insaid cylinder, an impact element, means providing a pressuretransmitting connection between said piston and impact element, theresistance of which is momentarily decreased during the power stroke ofthe apparatus, means for opening said inlet valve, and mechanismoperated by the movement of said piston for closing said inlet valve andopening the exhaust valve.

23. In apparatus of the character described, the combination of a ram, aplunger, a hydraulic cylinder, a chamber which is put into communicationwith the hydraulic cylinder during the power stroke of the apparatus, amotive fluid cylinder adapted to receive an expansible fluid andprovided with inlet and exhaust ports, valves to control said ports, apiston in said motive fluid cylinder connected with said plunger, meansfor opening said inlet valve, and mechanism automatically operated forclosing the inlet valve and opening and closing said exhaust valve.

24. In hydraulically operated apparatus, the combination with ahydraulic cylinder, a ram, a plunger and a steam cylinder, a piston foroperating said plunger, said cylinder having inlet and exhaust ports andvalves to control the same, of mechanism for automatically closing saidinlet valve comprising a bell crank connected with said piston so as tobe rocked thereby, a dog carried by said bell crank, a spring againstthe force of which the valve is opened, a cam engaged by said dog whichserves to hold the valve open, and a trip device for tripping said dogto release the cam.

25. In hydraulically operated apparatus, the combination with ahydraulic cylinder, a ram, a plunger and a steam cylinder, a piston foroperating said plunger,'said cylinder having inlet and exhaust ports andvalves to control the same, of mechanism for automatically closing saidinlet valve comprising a bell crank connected with said piston so as tobe rocked thereby, a dog carried by said bell crank, a spring againstthe force of which the valve is opened, a cam engaged by said dog whichserves to hold the valve open, and a trip device for tripping said dogto release the cam which. is

naeoaea adjustable to vary the point at which the dog is tripped.

26. in hydraulically operated apparatus, the combination with ahydraulic cylinder,

valve when the'dog is tripped and disen gaged from the cam.

27. In hydraulically operated apparatus, the combination with ahydraulic cylinder, a ram, a plunger and a steam cylinder, a piston foroperating the plunger, said cylinder having inlet and exhaust ports, andvalves to control the same, of a rocking device for opening and closingthe exhaust valve comprising a rod carried by said piston, a sleeve onsaid rod, a lever on which said exhaust valve is supported, linksconnecting said lever with the sleeve, a dog which engages said lever tohold said exhaust valve open, a head on said rod adapted to engage saidsleeve so as to open the exhaust valve and to engage said rocking deviceto disengage the dog from said lever, and a spring to seat the exhaustvalve.

28. The method of utilizing an expansible motive fluid for the operationof impact apparatus which consists in momentarily reducing theconnection between the power driven element and the. impact element andshutting ofl the flow of the expansive motive fluid to said drivenelement, and confining a volume of said motive fluid so that it actsexpansively against said driven element at the time the resistance ofsaid connection is reduced.

29. The method of utilizing an expansible motive fluid for the operationof hydraulic impact apparatus which consists in momentarily reducing theresistance of the pressure transmitting fluid against the power drivenand impact elements by increasing the capacity of the means confiningsaid pressure transmitting fluid and shutting ofi the flow .oifexpansible motive fluid to the driven element and confining a volume ofsaid fiuid so that it will act expansively against said driven elementat the time the resistance of the pressure transmitting fluid isreduced.

30. The method of utilizing'an expansible motive fluid for the operationof hydraulic impact apparatus which consists in momen tarily reducingthe connection between the driven element and the impact element byputting into communication with the hydraulic cylinder a space intowhich a portion of the pressure transmitting fluid may enter, varyingthe effect of such reduction of resistance by allowing a regulatableflow of fluid from the cylinder to said space before the space is putinto direct communication with the interior of the cylinder, andshutting off the flow of the expansive motive fluid to said drivenelement, and confining a volume of said motive fluid so that it actsexpansively against said driven element at the time the resistance ofthe pressure transmitting fluid is reduced.

31. The method of intensifying the power stroke of a hydraulic impactapparatus v which consists in putting in direct communication with thehydraulic cylinder, a space into which the pressure transmitting fluidmay enter suddenly so that the resistance of the pressure transmittingfluid is momentarily decreased and varying the extent of the decrease ofsaid resistance ,by allowing a certain amount of the pressuretransmitting fluid to flow regulatably into said space before the spaceis put in direct communication with the cylinder.

- LADISLAV F. KRISTUFEK

